This invention relates to reactive gaseous deposition precursor feed apparatus, and to chemical vapor deposition methods.
Semiconductor processing in the fabrication of integrated circuitry typically includes the deposition of layers on semiconductor substrates. Exemplary processes include physical vapor deposition (PVD) and chemical vapor deposition (CVD). In the context of this document, xe2x80x9cCVDxe2x80x9d includes any process, whether existing or yet-to-be developed, where one or more vaporized chemicals is fed as a deposition precursor for reaction and adherence to a substrate surface. By way of example only, one such CVD process includes atomic layer deposition (ALD). With typical ALD, successive mono-atomic layers are adsorbed to a substrate and/or reacted with the outer layer on the substrate, typically by successive feeding of different precursors to the substrate surface.
Chemical vapor depositions can be conducted within chambers or reactors which retain a single substrate upon a wafer holder or susceptor. One or more precursor gasses are typically provided to a shower head within the chamber which is intended to uniformly provide the reactant gasses substantially homogeneously over the outer surface of the substrate. The precursors react or otherwise manifest in a deposition of a suitable layer atop the substrate. Plasma enhancement may or may not be utilized, and either directly within the chamber or remotely therefrom.
In certain chemical vapor deposition processes, including ALD, precursors are pulsed or otherwise intermittently injected into the reactor for adsorption onto a substrate or for reaction and/or deposition onto a substrate. In one prior art construction and method, a fixed volume chamber is provided with an in-feed end and with an out-feed end which feeds to a deposition chamber. A feed valve is upstream of the in-feed end, and an output valve is received between the out-feed end and the deposition chamber. A constant flow is provided to the reservoir through the in-feed valve and the output valved is periodically pulsed to provide pulsed flow to the chamber.
The invention was motivated in addressing the above-described issues, although it is in no way so limited. The invention is only limited by the accompanying claims as literally worded without interpretative or other limiting reference to the specification or drawings, and in accordance with the doctrine of equivalents.
The invention includes reactive gaseous deposition precursor feed apparatus and chemical vapor deposition methods. In one implementation, a reactive gaseous deposition precursor feed apparatus includes a gas passageway having an inlet and an outlet. A variable volume accumulator reservoir is joined in fluid communication with the gas passageway. In one implementation, a chemical vapor deposition method includes positioning a semiconductor substrate within a deposition chamber. A first deposition precursor is fed to an inlet of a variable volume accumulator reservoir. With the first deposition precursor therein, volume of the variable volume accumulator reservoir is decreased effective to expel first deposition precursor therefrom into the chamber under conditions effective to deposit a layer on the substrate.